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Automatic transmission having torque converter with lockup clutch and method of controlling same lockup clutch

a technology of torque converter and lockup clutch, which is applied in the direction of fluid gearing, gearing, instruments, etc., can solve the problem of not fixing the lockup oil pressure, and achieve the effect of preventing the occurrence of shock

Inactive Publication Date: 2008-04-29
TOYOTA JIDOSHA KK
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Benefits of technology

[0013]The invention has been accomplished in order to solve the above-stated problems. It is an object of the invention to provide an automatic transmission system having a lockup clutch, which is capable of preventing a delayed downshift during a decelerating run of the vehicle in a fuel-cut state and which is capable of avoiding a completely locked-up state regardless of the situation of a shift and of substantially preventing occurrence of a shock, and a method of controlling the same lockup clutch.

Problems solved by technology

Furthermore, in a shift situation that will likely lead to complete engagement of the lockup clutch (e.g., a situation where the slip rotation speed is low), the lockup oil pressure is not fixed, but the normal feedback control is executed.

Method used

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  • Automatic transmission having torque converter with lockup clutch and method of controlling same lockup clutch
  • Automatic transmission having torque converter with lockup clutch and method of controlling same lockup clutch
  • Automatic transmission having torque converter with lockup clutch and method of controlling same lockup clutch

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Embodiment Construction

[0048]Preferred embodiments of the invention will be described hereinafter with reference to the accompanying drawings. In the drawings, like component parts are represented by like reference characters. Such like component parts will be referred to by the same names below, and perform the same functions. Therefore, repeated description of those component parts and the like will be avoided.

[0049]FIG. 1 shows a diagram illustrating control blocks of an automatic transmission system according to one embodiment of the invention, which is applied to a vehicle and includes an ECT-ECU (electronically controlled automatic transmission-electronic control unit) 100, an engine 110, a torque converter 120, an automatic transmission 200, and sensors and the like that are interconnected. The automatic transmission 200 includes an oil pump 202, a pressure regulating valve 204, and a speed change mechanism 300. The torque converter 120 includes a lockup clutch 122, the oil pressure of which is con...

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Abstract

When a downshift instruction has been detected, the oil pressure of a lookup clutch is controlled, and the state of operation of the automatic transmission is detected. If a starting condition has been met, a slip rotation speed of the lockup clutch is calculated, and if the calculated slip rotation speed is greater than or equal to a reference rotation speed, the calculated slip rotation speed is set as a target slip rotation speed. If a condition for converging the target slip rotation speed has been met, the target slip rotation speed is then converged to a steady target rotation speed.

Description

INCORPORATION BY REFERENCE[0001]The disclosure of Japanese Patent Application No. 2002-326828 filed on Nov. 11, 2002, including the specification, drawings and abstract is incorporated herein by reference in its entirety.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The invention relates to a technology for controlling an automatic transmission of a vehicle at the time of a downshift while the vehicle is coasting in a fuel-cut state and, more particularly, to a technology for controlling a lockup clutch provided in a torque converter of the automatic transmission.[0004]2. Description of the Related Art[0005]While a vehicle is coasting in a fuel-cut state, a control of oil pressure of a lockup clutch is sometimes executed in order to prevent a rapid fall of the engine rotation speed. For example, Japanese Patent Application Laid-Open Publication No. 6-331023 (patent literature I) discloses a technology in which the oil pressure of the lockup clutch is controlled so ...

Claims

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Application Information

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IPC IPC(8): F16H61/14
CPCF16H61/143F16H2061/145F16H2061/0496Y10T477/735Y10T477/635Y10T477/688Y10T477/753F16H2061/146
Inventor AYABE, ATSUSHISUGIMURA, TOSHIOKAWAMURA, TATSUYA
Owner TOYOTA JIDOSHA KK